This invention relates generally to compressor units of the wobble plate type, and, in particular, to a support mechanism of the wobble plate in such compressor units. In a known compressor unit, the rotation of the drive shaft is converted into reciprocating motion through a cam rotor having a sloping end surface mounted on an end of the drive shaft and a wobble plate disposed on the sloping surface through a needle bearing therebetween. The wobble plate is supported on a fixed member such as a cylinder block in such a manner that the wobble plate is prevented from rotating but is nutatable or able to wobble. Thus, the wobble plate wobbles by the rotation of the cam rotor, and the piston rods connected to the wobble plate are reciprocated to compress fluid within cylinders.
This compressor unit has been known to be generally suitable for, and has been commercially used for, refrigerant compressors in cooling systems for automobiles.
In a known supporting mechanism of the wobble plate, a bevel gear is fixed to the wobble plate at the center thereof and another bevel gear engaging the bevel gear of the wobble plate is supported on the cylinder block in such a manner that the rotation of the another bevel gear is prevented. Both of the bevel gears are provided with a ball seat at their centers, and a bearing ball is seated in the ball seats. Thus, the wobble plate is prevented from rotating by the engagement between both bevel gears and is able to nutate along the ball surface.
A deficiency in this mechanism is that considerable noise is produced by the engagement between the both bevel gears in the operation of the compressor.
In another known mechanism, the wobble plate is supported by a bearing ball similar to the above described mechanism but the rotation of the wobble plate is prevented by a pin fixed to the lower end of the wobble plate. The pin is slidably fitted in an axial groove formed in an inner wall of the compressor housing.
In this arrangement, the pin reciprocates along the groove with a considerable sliding friction between the pin and the groove wall thereby introducing a power loss. Furthermore, the pin is subjected to an undesired force so that the reliability of the pin and the compressor unit as a whole is thus degraded, and the compressor housing is required to be large because the groove must be formed therein.
Yet another known wobble plate supporting mechanism comprises a universal hook joint connected to and end of the wobble plate, with the other end of the wobble plate being fixed to the cylinder block. In this arrangement, the hook joint is subjected to an undesired considerable radial load, so that the reliability of the mechanism is degraded.